In a computer network such as the Internet, each node in the network has an address. A computer system resident at a particular address may have sufficient bandwidth or capacity to receive data from, and to transmit data to, many other computer systems at other addresses. An example of such a computer system is a server, many commercial versions of which can simultaneously exchange data with thousands of other computer systems.
A computer system at another location may have only sufficient bandwidth to effectively exchange data with only one other computer system. An example of such a system is an end user's personal computer connected to the Internet by a very low speed dialup modem. However, even typical personal computers connected to the Internet by higher speed dialup modems may have sufficient bandwidth that they may exchange data essentially simultaneously in an effective manner with several other computer systems. Moreover, an end user's personal computer system may have even greater bandwidth when connected to the Internet by ISDN lines, DSL (e.g., ADSL) lines, cable modems, T1 lines or even higher capacity links. As discussed more fully below, various embodiments of the present invention may take advantage of the availability of such higher capacity end user systems (e.g., those computer systems capable of essentially simultaneously exchanging data with multiple computer systems).
In a typical situation, as shown in FIG. 1, a content provider distributes its data by making the data available on a server node 8 simultaneously to a plurality of users at user nodes 12 (of note, the terms “server”, “root server” and “primary server” may be used interchangeably throughout the present application to refer to the same device (i.e., the highest level parent node in a given network). The double-headed arrows show the two-way communication between each end user's computer system and the server. Essentially the content provider's server transmits a separate stream of signals to each receiver node. To accommodate additional users, the content provider would typically either add equipment to increase capacity or it would engage a mirror site to accomplish essentially the same result as adding equipment. The capacities of the end user computers is of virtually no consequence in such a system.
Another system for distributing data is the Napster™ music file exchange system provided by Napster, Inc. of Redwood City, Calif. A schematic of the Napster™ music file exchange system (as its operation is presently understood) is illustrated in FIG. 2.
More particularly, it is believed that in the Napster™ system a copy of the music data is not kept on the server. The server 9 instead maintains a database relating to the various music files on the computers of users who are logged onto the server 9. When a first user 12a sees that a desired music file is available from a second logged on user 12b, the first user causes his computer to query the server 9 for the second user's node address and a connection is made between the first and second user's computers through which the first user's computer notifies the second user's computer of the desired file and the second user's computer responds by transmitting a copy of the desired music file directly to the first user's computer. It is further believed that a first user attempting to download a particular file from a second user must start completely over again if the second user cancels its transmission or goes off line during the data transfer.
In another area, engineers have developed what is known as “streaming media.” In summary, streaming media is a series of packets (e.g., of compressed data), each packet representing moving images and/or audio.
To help understand streaming media in more detail, it is helpful to review the traditional Internet distribution method. Each node (whether it is a server node or a user node) in a computer network has a unique identification (sometimes referred to as an “IP” address) associated with it. On the Internet, the unique address may be referred to as a Uniform Resource Locator (“URL”). A user desiring to obtain data from a particular server enters that server's URL into the user's browser program. The browser program causes a connection request signal to be sent over the Internet to the server. If the server has the capacity to accept the connection, the connection is made between the server and the user node (files requested by the user are typically transmitted by the server in full to the user node and the browser program may store the files in buffer memory and display the content on the user's computer system monitor—some files may be more permanently stored in the computer system's memory for later viewing or playing.) The connection with the server is typically terminated once the files have been received at the user node (or the connection may be terminated a short time thereafter). Either way, the connection is usually of a very short time duration.
With streaming media, the contact between the server and user nodes is essentially continuous. When a connection between a server node and user node is made and streaming media is requested, the server sends streaming media packets of data to the user node. A streaming media player installed on the user's computer system (e.g., software, such as RealMedia™ from RealNetworks, Inc. of Seattle, Wash.,) causes the data to be stored in buffer memory. The player decompresses the data and begins playing the moving images and/or audio represented by the streaming media data on the user's computer system. As the data from a packet is played, the buffer containing that packet is emptied and becomes available to receive a new packet of data. As a result, the memory assets of a user's computer are not overly taxed. Continuous action content, such as, for example, the display of recorded motion picture films, videos or television shows may be distributed and played in essentially “real time,” and live events, such as, for example, concerts, football games, court trials, and political debates may be transmitted and viewed essentially “live” (with only the brief delays needed for compression of the data being made available on the server, transmission from the server to the user node, and decompression and play on the user's computer system preventing a user from seeing the event at the exact same moment in time as a person actually at the event). And, when the systems are working as designed, the server node and user node may stay connected to each other until all the packets of data representing the content have been transmitted.